Answer:
A. Height of tomato plants
Step-by-step explanation:
The dependent variable in an experiment is the variable that the experimenter measures or the variable that responds to changes made to the independent variable. The dependent variable is dependent on the independent variable.
In this experiment conducted to determine how different PH values of soil will affect the growth of tomato plants, the growth of the plants is measured by their height. Hence, the dependent variable is the HEIGHT OF THE PLANTS.